In a trial set to begin next month, Silicon Valley workers allege that some of the tech industry’s biggest players conspired to fix wages between 2005 and 2009. But when it came to bringing the upstart Facebook into the mix, the social media company didn’t return their messages.

The suit, which was granted class certification in October, says that Google, Apple, Intel and Adobe Systems agreed not to poach one another’s employees, as well as consult one another before making strategic moves or starting new recruiting initiatives. The class consists of 64,000 employees seeking $3 billion in damages.

The original suit also named Pixar, Lucasfilm and Intuit, and the class contained 150,000 employees. However, those companies have agreed to settlements totaling $20 million, pending approval from a judge.

In recently released documents, the companies also attempted to bring Facebook on board, but the social media giant refused to play ball. According to U.S. District Judge Lucy Koh, Intuit chairman and partnership broker Bill Campbell “unsuccessfully sought to expand Google's anti-solicitation agreements to Facebook.”

The suit claims that over the course of the agreement, the technology companies became worried about the talent that Facebook was poaching from others in Silicon Valley. Google co-founder Sergey Brin wrote to Google employees in 2007, “The Facebook phenomenon creates a real retention problem, I now realize, not just because of FB's direct hiring, but the more insidious effect that everyone wants to start the next Facebook or get rich by having a popular fb app.”

In response, Campbell sent an email to Google executives, saying, “Who should contact Sheryl ( Sandberg ) or Mark (Zuckerberg ) to get a cease-fire? We have to get a truce.” However, as revealed by the Wall Street Journal, Sandberg told the court that Facebook wanted no part of an agreement, saying in recent documents, “I declined at that time to limit Facebook's recruitment or hiring of Google employees.”

On March 28, Koh denied a request by the companies to rule in their favor without a trial. The trial is scheduled to begin on May 27.

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